Math series formulas

Question 1

arithmetic series formula (2)

Answer 1

an=dn+a0
an=a1+d(n-1)

Question 2

sum of arithmetic series

Answer 2

Sn=(a1+an)(n/2)

Question 3

geometric series (3)

Answer 3

an=a1(r)^n-1
an=a0(r)^n
an=am(r)^n-m

Question 4

sum of geometric series

Answer 4

(a1[1-r^n]) / (1-r)

Question 5

infinite sum of geometric series

Answer 5

if -1<r<1
S = (a1) / (1-r)

Question 6

Sigma with x on top, y on bottom

Answer 6

sigma = sum
(x-y)+1 terms